This invention relates to methods, apparatus, and catheters that may be used to administer a therapeutic electrical pulse, such as an atrial defibrillation pulse, to the heart of a patient in need of such treatment.
Atrial fibrillation (AF) is the most common arrhythmia in humans and represents a significant public health problem. There are presently 2.2 million cases of AF in the United States and approximately 160,000 new cases diagnosed each year. AF is typically managed by a combination of anti-arrhythmic drugs and external or internal electrical cardioversion. In addition, surgical compartmentalization or radiofrequency ablation of atrial tissue can be used. Unfortunately, long term success rates are low; AF recurrence is high with both drug treatment and electrical cardioversion with internal and external shocks.
Internal electrical cardioversion of AF remains an uncomfortable therapy option for managing patients with AF. Even with recent advancements, shock voltages necessary to defibrillate the atrial, while considerably lower than that for the ventricles, are still beyond the pain threshhold. One reason high voltages may be necessary is that the main generator for AF is the left atrium and direct access to the left atrium is problematic because of the risk of embolism. Typically, atrial defibrillation lead locations are limited to right sided chambers (right atrium and right ventricle) and venous structures accessible from the right side of the heart (coronary sinus).
To create a trans-atrial shocking vector, the most common approach is to shock between one or more electrodes on the right side of the heart (right atrial appendage, superior vena cava, or right ventricle) to an electrode on the left side of the heart in the distal coronary sinus. The left atrium is also an important atrial chamber to defibrillate since (i) it can fibrillate independent of the right atrium, (ii) mapping studies have shown that earliest sites of activation following failed defibrillation arise from the left atrium for most defibrillation electrode configurations, (iii) early sites in or near the pulmonary veins have been shown to be responsible for the initiation of and early reoccurence of AF in many patients, and (iv) ablation of right atrial structures alone has had poor success in terminating AF or preventing its reoccurence. Nevertheless, there remains a need for means of defibrillating the atria of a subject without unduly high energy defibrillation pulses that would be painful to the subject being treated.
A first aspect of the present invention is an implantable system for the defibrillation of the atria of a patient""s heart. The system comprises (a) a first catheter configured for insertion into the right atrium of the heart (in one embodiment preferably without extending into the right ventricle of the heart); a first atrial defibrillation electrode carried by the first catheter and positioned at Bachmann""s bundle or at the atrial septum of the heart (i.e., a Bachmann""s bundle or an atrial septum electrode); (b) a second atrial defibrillation electrode which together with the first atrial defibrillation electrode provides a pair of atrial defibrillation electrodes that are configured for orientation in or about the patient""s heart to effect atrial defibrillation, and (c) a pulse generator operatively associated with the pair of atrial defibrillation electrodes for delivering a first atrial defibrillation pulse to the heart of the patient. The second electrode may be configured for positioning through the coronary sinus ostium and in the coronary sinus or a vein on the surface of the left ventricle, such as the great vein. As explained further below, an additional electrode configured for positioning in the superior vena cava, right atrium (including the right atrial appendage, or the right ventricle may also be included, and the pulse generator may be configured or programmed for concurrently delivering a first defibrillation pulse through the additional electrode and the atrial septum electrode, and a second defibrillation pulse through the atrial septum electrode and the second electrode.
A second aspect of the present invention is a catheter assembly useful for the defibrillation or cardioversion of a patient""s heart. The assembly comprises: (a) a first transveneous catheter configured for insertion into the heart of the patient, the first transvenous catheter having a proximal end portion, a distal end portion, and an elongate intermediate portion therebetween, and with the first transveneous catheter having a first electrode connected thereto; (b) a second transveneous catheter configured for insertion into the heart of the patient, the second transveneous catheter having a proximal end portion, a distal end portion, and an elongate intermediate portion therebetween; and (c) a connecting member attached to the first transveneous catheter, with the connecting member connected to the second transveneous catheter intermediate portion.
A further aspect of the present invention is a method for the defibrillation or cardioversion of the heart of a patient in need thereof while minimizing or reducing the voltage of the defibrillation pulses to be delivered. The method comprises the steps of: (a) positioning first and second defibrillation electrodes in operable association with the heart of the subject, the first and second defibrillation electrodes defining a gradient field in the heart, the gradient field including a region of the heart to be defibrillated; (b) positioning a third electrode in the gradient field between the first and second electrodes; and then (c) concurrently delivering (i) a first defibrillation pulse between the first and third electrode and (ii) a second defibrillation pulse between the second and third electrodes; with the first and second defibrillation pulses together effective to defibrillate the heart. The voltage required for each of the first and second defibrillation pulses is preferably less than the voltage necessary for a single defibrillation pulse delivered between the first and second electrodes that is effective to defibrillate the heart. One, two or three or more additional electrodes may be positioned between the first, second and third electrodes to further reduce the voltage required, with additional shocks being delivered concurrently between various combinations of the electrodes (typically between adjacent electrodes).
A further aspect of the present invention is an implantable system for the defibrillation or cardioversion of a patient""s heart. The system comprises: (a) first and second defibrillation electrodes configured for positioning in operable association with the heart of the subject, the first and second defibrillation electrodes when so positioned defining a gradient field in the heart between the first and second electrodes and in a region to be defibrillated; (b) a third defibrillation electrode configured for positioning in the gradient field between the first and second electrodes; and (c) a pulse generator operatively associated with the first, second and third defibrillation electrodes and configured for concurrently delivering (a) a first defibrillation pulse between the first and third electrode and (b) a second defibrillation pulse between the second and third electrodes. The two pulses are together effective to defibrillate the heart. Preferably, the voltage required for each of the first and second defibrillation pulses is less than the voltage required for a single defibrillation pulse delivered between the first and second electrodes that is effective to defibrillate the heart. Such an apparatus may be configured to carry out the methods described above.
In preferred embodiments of the foregoing methods and systems, there is further provided first and second transveneous catheters, wherein the first, second and third electrodes are carried by the first and second transveneous catheters, and wherein the first transveneous catheter is fixed to the second transveneous catheter.
In particularly preferred embodiments of the foregoing methods and systems, the first and second electrodes are carried by a first transveneous catheter, the first transveneous catheter having a proximal end portion, a distal end portion, and an elongate intermediate portion therebetween. The third electrode is carried by a second transveneous catheter, the second transveneous catheter having a proximal end portion, a distal end portion, and an elongate intermediate portion therebetween. The second transveneous catheter distal end portion is connected to the first transveneous catheter intermediate portion through a connecting member, as described in connection with catheter assemblies above. The third electrode is then, preferably, an atrial septum electrode.
A further aspect of the present invention is an implantable system for the electrical treatment/defibrillation of the atria of a patient""s heart, the system comprising: a first atrial therapeutic electrode configured for stimulating Bachmann""s bundle and for positioning on or adjacent Bachmann""s bundle along the superior aspect of the atrium and adjacent to the atrial septum; a second atrial electrode which together with the first atrial electrode provides a pair of atrial electrodes; and a pulse generator operatively associated with the pair of atrial electrodes for delivering an atrial defibrillation or other therapeutic pulse. Methods of delivering an atrial defibrillation pulse, or other therapeutic pulse, by positioning electrodes as described above are a further aspect of the invention. The first atrial electrode may be carried by a first catheter, with the first catheter configured for insertion into the right atrium of the heart, preferably without extending into the right ventricle of the heart. The second atrial electrodes may be positioned as described in connection with second electrodes corresponding to or paired with atrial septum electrodes as described herein.
A further aspect of the present invention is a method for the electrical treatment or defibrillation of the atria of a patient""s heart, comprising the steps of: providing a set of atrial therapeutic electrodes for defibrillating the patient""s heart, or otherwise administering a therapeutic electric pulse to the patients heart, the set including a first atrial electrode positioned in the superior vena cava of the patient; delivering a first therapeutic electric pulse such as a defibrillation pulse to the atria of the heart, and then delivering a second therapeutic electric pulse such as a defibrillation pulse pulse to the atria of the heart, wherein at least one of the first and second pulses is delivered with the first atrial defibrillation electrode. Sets of atrial therapeutic or defibrillation electrodes that may be used to carry out this method include but are not limited to the sets of atrial defibrillation electrodes described herein. For example, the set of atrial electrodes may further comprise a second atrial therapeutic or defibrillation electrode positioned in the coronary sinus of the heart, and at least one of the first and second pulses may be delivered with the second atrial electrode. In one embodiment, at least one of the first and second therapeutic pulses is delivered between the first and second therapeutic electrodes.
A further aspect of the present invention involves the balancing of peak amplitudes for defibrillating the atria or ventricles of a patient""s heart, or otherwise delivering a therapeutic electric pulse to the atria or ventricles of a patient""s heart. The method comprises: delivering a first therapeutic electrical pulse such as a defibrillation pulse to the atria or ventricles of the heart, and then delivering a second therapeutic electric pulse such as a defibrillation pulse to the atria or ventricles of the heart, wherein the total energy, or leading edge peak voltage, of the second pulse is at least 90 or 95% of the total energy, or leading edge peak voltage, of the first pulse. Sets of treatment electrodes that may be used to carry out this method include but are not limited to the sets of atrial treatment electrodes described herein. An apparatus configured to carry out this method (e.g., employing two separate discharge capacitors operatively associated with a power supply and a controller, with the controller configured so that the first capacitor is discharged by the controller to administer the first pulse and the second capacitor is discharged by the controller to administer the second pulse; or with a single capacitor having sufficient storage capacity so that the aforesaid energy or voltage features can be achieved through wave shaping through the controller) is a further aspect of the invention.
A still further aspect of the present invention is a transveneous catheter for stimulating the heart of a patient at separate locations therein, the catheter comprising: a catheter body having a proximal portion, an intermediate portion and a distal portion; a first electrode connected to the catheter body distal portion; a catheter appendage having a proximal portion and a distal portion, the appendage proximal portion connected to the catheter body intermediate portion; and a second electrode connected to the appendage distal portion. In one embodiment of the foregoing, the catheter body is configured for insertion into the right ventricle of the heart. In a particular embodiment of the foregoing, the catheter body is configured for insertion through the coronary sinus ostium and into the coronary sinus of the heart. The second electrode of the catheter may be an aterial electrode, such as an atrial septum electrode or a Bachmann""s bundle electrode.
The foregoing and other objects and aspects of the present invention are explained in greater detail in the drawings herein and the specification set forth below.